Many chemical reactions are catalyzed by acidic catalysts. The acidic catalyst may be used in a homogeneous or heterogeneous mode, i.e. the catalyst can be dissolved in the reactant-containing solution or the catalyst may exist in a different phase than the reactant and/or the reaction products. Homogeneous acid catalysts may have certain advantages over heterogeneous acid catalysts, such as increased activity or selectivity, provided separation of the reaction products from the catalyst is easily carried out. Since such separation may be difficult, many times a heterogeneous acid catalyst is preferred, even when the activity or selectivity is less than a homongeneous catalyst in the same reaction. One widely used class of heterogeneous acid catalysts is the solid polystyrene sulfonic acids. These polymers are known to be effective as acid catalysts for many reactions, but, due to the organic polymer backbone, are not always as stable as desired. Moreover, the organic nature of the polymer may hinder polar reactants from contacting the functional sulfonic acid sites. In addition, the well known high temperatures utilized to remove such organic tars and crud from inorganic acid catalysts, such as zeolites, of course, cannot be used to reactivate polystyrene sulfonic acids because of the thermal instability of the organic polymer backbone.